CakeML/cakeml

Implement lexer on mlstrings

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#353 opened on Oct 26, 2017

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help wanted

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Description

The CakeML lexer operates on a char list. Therefore the first thing the CakeML compiler does after reading in its input string is explode the string into a list. This is wasteful: I think the lexer can easily be made to work on mlstrings.

This issue is to make the lexer operate on mlstrings and update the compiler accordingly to avoid the explode.

Extension thoughts:

  • The sexp-parsing option would still need to explode the input because the sexp parser operates on char lists in a possibly more unavoidable way. (This issue does not require avoiding the explode for sexps.)
  • For large input, we might want to be even more sophisticated and lex/parse/typecheck incrementally, to catch errors before reading in all the source code. (Obviously this issue doesn't require doing that.)

Contributor guide

Research direction
Study the current lexer implementation to understand how it works on char lists, then explore the mlstring type and adapt the lexer functions accordingly. Look at the compiler's entry point where `explode` is called and replace it.
Tech stack
None
Domain
compilers
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitStandard ML basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40